Chemistry

Chemical Reactions and Equations

684 Questions

Chemical reactions and equations form a foundational chemistry topic where students identify reaction products, balance chemical formulas, and classify reaction types. It covers critical mechanisms like Markovnikov's rule, precipitation, and endothermic or exothermic processes. These questions are highly common in general science sections of state and central government competitive exams.

Endothermic reactionsPrecipitation reactionsDehydrohalogenation of alkyl halidesChemical equation balancingReaction product identification

Chemical Reactions and Equations Questions

Multiple choice

NADP can react with ________ to form NADPH.

  1. hydrogen

  2. oxygen

  3. carbon

  4. nitrogen
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

NADP+ is reduced to NADPH by accepting a hydrogen atom (which consists of a proton, H+, and an electron, e-). The reaction is: NADP+ + H+ + 2e- → NADPH. This occurs during the light-dependent reactions of photosynthesis. Oxygen, carbon, and nitrogen are not involved in this specific reduction reaction.

Multiple choice

NADP can react with ______ to form NADPH.

  1. hydrogen

  2. oxygen

  3. carbon

  4. nitrogen
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

NADP+ gains a hydrogen ion (H+) and two electrons to become NADPH, the reduced form that carries energy to the Calvin cycle. This reduction occurs during the light-dependent reactions of photosynthesis when water molecules are split.

Multiple choice

The phthalic acid and anisole are synthesised by

  1. Gabriel and Williamson synthesis

  2. Williamson and Gattermann Koch synthesis

  3. Wohler and Gabriel synthesis

  4. Wohler and Gattermann Koch synthesis

  5. Fischer-tropsch and Williamson synthesis
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is correct because phthalimide is first of all treated with KOH to form potassium phathalimide, which is then heated with alkyl halides which gives N-alkyl phthalimide. Then, it is hydrolysed by the HCl to form phthalic acid, this is the Gabriel synthesis, while phenol reacts with diethyl sulphonate catalysed by strong base to form the anisole.

Multiple choice

In which of the following reactions, Pb/BaSO4 catalysis is used?

  1. Perkin reaction

  2. Tishchenko reaction

  3. Rosenmund reaction

  4. Clemmensen reaction

  5. Reformatsky reaction
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This option is correct because aldehydes are formed more easily to get reduced with acid chloride, but their reduction is checked by barium sulphate. The catalytic hydrogenation of acid chlorides allows the formation of aldehydes.

Multiple choice

Assertion: When acetylene reacts with methylmagnesium bromide, hydrogen is evolved. Reason: Grignard reagent is an organometallic compound of Mg+2.

  1. Both A and R are true and R is the correct explanation of A.

  2. Both A and R are true but R is not the correct explanation of A.

  3. A is true but R is false.

  4. A is false but R is true.

  5. Both A and R are false.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This option is correct because when acetylene reacts with methylmagnesium bromide, CH4 is produced and methylmagnesium bromide (grignard reagent) is an organometallic compound of Mg+2.

Multiple choice

Which of the following statements is/are true? A. Benzene reacts with isobutyl chloride in presence of anhydrous AlCl3 to give isobutylbenzene. B. Reduction of 2-butyne with NaNH2 in liquid NH3 gives cis-2-butene. C. Baeyer’s reagent can be used to distinguish cyclopropane from propene.

  1. Only A

  2. Only B

  3. A and B

  4. A and C

  5. Only C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This option is correct because propene decolourises Bayer's reagent, but cyclopropane being saturated, does not. This option is wrong because statement A is false, while statement C is true.

Multiple choice

Assertion: Benzene reacts with Cl2 in presence of light to form BHC. Reason: BHC is also called gammexane or 666.

  1. Both A and R are true and R is the correct explanation of A.

  2. Both A and R are true but R is not the correct explanation of A.

  3. A is true but R is false.

  4. A is false but R is true.

  5. Both A and R are false.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct because of the correct explanation - in presence of light, free radical addition of Cl2 occurs to the three double bonds giving BHC.

Multiple choice

Assertion: Treatment of 1, 3-dibromopropane with zinc produces cyclopropane. Reason: The reaction of alkyl halides with zinc dust is called frankland reaction.

  1. Both A and R are true and R is the correct explanation of A.

  2. Both A and R are true but R is not the correct explanation of A.

  3. A is true but R is false.

  4. A is false but R is true.

  5. Both A and R are false.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct because of the correct explanation - the two carbon atoms carrying Br-atoms in 1, 3-dibromopropane are close and hence undergo intramolecular cyclization to give cyclopropane.

Multiple choice

Assertion: 1-Chlorobutane on heating with alcoholic KOH undergoes dehydrohalogenation to yield 1-butene as the major product. Reason: The reaction does not occur through carbocation intermediate but instead occurs by a concerted mechanism.

  1. Both A and R are true and R is the correct explanation of A.

  2. Both A and R are true but R is not the correct explanation of A.

  3. A is true but R is false.

  4. A is false but R is true.

  5. Both A and R are false.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is correct.

Multiple choice

The reaction of dianhydrides with diamines gives ________.

  1. Aromatic polyimide

  2. Aromatic polysulfides

  3. Polyethersulfone (PES)

  4. Aromatic polyether

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Aromatic polyimide are synthesized by the reaction of dianhydrides with diamines, for example, pyromellitic anhydride with ''p''-phenylenediamine. It can also be accomplished using diisocyanates in place of diamines.

Multiple choice

Redox reaction is when

  1. Oxidation reaction takes place

  2. Reduction reaction both takes place

  3. Oxidation and reduction both takes place together

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A redox reaction always involves both oxidation (loss of electrons) and reduction (gain of electrons) occurring simultaneously. Electrons lost by one species must be gained by another - they cannot exist freely. The term 'redox' itself comes from combining 'reduction' and 'oxidation'.

Multiple choice

When nitrobenzene is fused with KOH, it gives

  1. Ortho-nitrophenol and nitrosobezene

  2. Para-benzaquinone and nitrosobenzene

  3. Para-nitrophenol and para-benzaquinone

  4. Ortho-nitrophenol and para-nitrophenol

  5. (1) and (2) both
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This option is correct because benzene is activated by the nitro group when it is mostly fused with KOH to form ortho-nitrophenol and para-nitrophenol.